CD1d-unrestricted NKT cells are endowed with a hybrid function far superior than that of iNKT cells

Invariant natural killer T (iNKT) cells to date represent the best example of cells known to have a hybrid function, representing both innate and adaptive immunity. Shared phenotypic similarities with NK cells together with a rapid response to a cytokine stimulus and a productive TCR engagement are the features that underline the hybrid nature of iNKT cells. Using these criteria, we provide molecular and functional evidence demonstrating that CD1d-independent (CD1d^ind) NKT cells, a population of CD1d-unrestricted NKT cells, are endowed with a hybrid function far superior to that of iNKT cells: (i) an extensive shared program with NK cells, (ii) a closer Euclidian distance with NK cells, and (iii) the ability to respond to innate stimuli (Poly:IC) with cytotoxic potential in the same manner as NK cells identify a hybrid feature in CD1d^indNKT cells that truly fulfills the dual function of an NK and a T cell. Our finding that CD1d^indNKT cells are programmed to act like NK cells in response to innate signals while being capable of adaptive responses is unprecedented, and thus might reemphasize CD1d-unrestricted NKT cells as a subset of lymphocytes that could affect biological processes of antimicrobial and tumor immunity in a unique way.Natural killer T (NKT) cells are increasingly regarded as cells endowed with a hybrid function between an NK cell and a T cell (1, 2). The current classification of NKT cells places them into three categories: type I, type II, and NKT-like cells (1). Type I comprises invariant NKT (iNKT) cells that recognize the glycolipid α-galactosylceramide (α-GalCer) loaded into the MHC class I molecule, CD1d, and contain an invariant TCR repertoire of Vα14-Jα18 (3–5). Type II NKT cells are also CD1d dependent but do not respond to α-GalCer in the same way as iNKT cells do (6, 7). NKT-like cells encompass all other NKT cells and are CD1d independent (CD1d^ind) (8); they are by far the most heterogeneous and the least characterized.Recent studies have increasingly shown a shared expression of NK cell-related receptors on other effector cells. CD8⁺ T cells are known to up-regulate NK markers, such as NK1.1, and can even respond quickly like NK cells (9). Other work has described NKT cells that express NKp46 (10), a marker selectively associated with conventional NK cells and NK22 cells in the gut (11). Moreover, γδ T cells have been shown to express NK markers and display an innate-like response (12). Collectively, these reports converge to raise the following key questions. What qualifies as an NKT cell? Do the cells need to express only NK1.1 and CD3 to be eligible for NKT nomenclature? With the continuous development of both NK and T-cell fields, the simplistic definition that NKT cells are subsets of T cells that express the NK1.1 marker is becoming increasingly misleading and even inaccurate. For instance, NK1.1 complex is expressed in the BALB/c strain but there are allelic divergences with the polymorphism leading to the PK136 antibody not reacting to the BALB/c NK.1.1 (NKrp1) complex (13). This definition is also limited in the C57BL/6 strain because of the discovery of NK1.1⁻CD1d⁺ NKT cells (14). Although phenotypic similarities can be misleading, the criteria that best describes an NKT cell is the ability to perform with a hybrid function between an NK cell and a T cell (2).Nonetheless, the concept of hybrid function is also an elusive notion allowing for a gradient of functions. A number of works refer to an NKT hybrid function as the ability of a T cell with phenotypic similarities to NK cells to perform with innate-like response. The best example of cells endowed with a hybrid NKT cell function are thought to be iNKT cells (2). In this study, we provide molecular and functional evidence demonstrating that CD1d^indNKT cells—a population of MHC-unrestricted T cells—are endowed with a hybrid function that associates them to the NK cell lineage in a manner far superior to the known link between NK and iNKT cells. An extensive shared program with NK cells, a similarity in the gene expression profile with NK cells, and their ability to respond (like NK cells) not only to cytokine signals (IL-12 plus IL-18) but also to innate stimuli [in vivo treatment with Poly:IC (Fisher)] with massive production of key effector players of the cytotoxic pathway collectively identify a hybrid feature in CD1d^indNKT cells that uniquely fulfills the function of an NK cell and a T cell.     

Addiction to multiple oncogenes can be exploited to prevent the emergence of therapeutic resistance

Many cancers exhibit sensitivity to the inhibition of a single genetic lesion, a property that has been successfully exploited with oncogene-targeted therapeutics. However, inhibition of single oncogenes often fails to result in sustained tumor regression due to the emergence of therapy-resistant cells. Here, we report that MYC-driven lymphomas frequently acquire activating mutations in β-catenin, including a previously unreported mutation in a splice acceptor site. Tumors with these genetic lesions are highly dependent on β-catenin for their survival and the suppression of β-catenin resulted in marked apoptosis causally related to a decrease in Bcl-xL expression. Using a novel inducible inhibitor of β-catenin, we illustrate that, although MYC withdrawal or β-catenin inhibition alone results in initial tumor regression, most tumors ultimately recurred, mimicking the clinical response to single-agent targeted therapy. Importantly, the simultaneous combined inhibition of both MYC and β-catenin promoted more rapid tumor regression and successfully prevented tumor recurrence. Hence, we demonstrated that MYC-induced tumors are addicted to mutant β-catenin, and the combined inactivation of MYC and β-catenin induces sustained tumor regression. Our results provide a proof of principle that targeting multiple oncogene addicted pathways can prevent therapeutic resistance.Cancer cells are highly sensitive to the targeted inhibition of single driver mutations, eliciting a phenomenon known as “oncogene addiction” (1). The identification of genetic dependencies in multiple tumor types has resulted in the development of several molecularly targeted therapeutics, including the BCR-ABL kinase inhibitor imatinib for the treatment of chronic myelogenous leukemia (CML), the EGFR kinase inhibitor gefitinib for the treatment of non–small cell lung cancer (NSCLC), and the BRAF kinase inhibitor vemurafenib for the treatment of advanced melanoma (2–4). Although these oncogene-targeted agents have provided promising clinical responses, many patients ultimately experience a recurrence of their disease due to the development of drug resistance (4–6). Thus, it has become evident that monotherapy with targeted drugs is insufficient for achieving sustained tumor regression.Resistance to targeted therapy can arise through multiple mechanisms, depending on the tumor type and the targeted oncogenic pathway (7). Cells frequently acquire resistance through mutations in the targeted oncogene itself that disrupt drug binding, as in the case of BCR-ABL and EGFR (8, 5, 6). In addition, resistance to EGFR inhibition in NSCLC and BRAF inhibition in melanoma has been found to occur through a variety of mechanisms that activate downstream signaling proteins or alternative pathways, which can functionally substitute for loss in activity of the targeted oncogene (9–11). Although significant progress has been made in the identification and inhibition of resistance pathways, it may prove challenging to anticipate and suppress all of the potential mechanisms of resistance for each oncogene-addicted cancer and targeted therapeutic agent.Combination therapy has been successfully applied to prevent resistance in the treatment of infectious diseases such as HIV (12, 13) and tuberculosis (14). In the context of oncogene-targeted therapy for cancer, it has been proposed that a similar strategy, using combinations directed against multiple dependencies, is the most likely to prevent resistance (7). Indeed, mathematical modeling indicates that targeting at least two independently required pathways may be sufficient to prevent tumor recurrence (15). However, there exists little experimental evidence directly testing such an approach and it remains unclear which combinations of targets would be most effective at inducing long-term remissions.MYC is one of the most frequently amplified oncogenes in human cancer (16). In the Eμ-tTA/tetO-MYC conditional mouse model, overexpression of MYC results in the development of aggressive T-cell lymphoma, and MYC inactivation in established tumors is sufficient to induce tumor regression through processes such as proliferative arrest, cellular senescence, apoptosis, and the shutdown of angiogenesis (17–19). The extent of regression is dependent on both cell-intrinsic and host-dependent contexts, and in particular, tumors frequently recur following MYC inactivation in the absence of an intact adaptive immune system (20). Recurring tumors restore expression of the MYC transgene or up-regulate expression of endogenous Myc, demonstrating that resistance occurs primarily through reactivation of the MYC pathway (21). Thus, MYC oncogene addiction and tumor recurrence in the Eμ-tTA/tetO-MYC lymphoma model resembles the clinical course of human cancers treated with single agent targeted therapy.Here, we demonstrate that the combined inactivation of two oncogene addiction pathways can result in sustained tumor regression. Moreover, we describe a previously unidentified splice acceptor site mutation in β-catenin that is associated with MYC-induced lymphomagenesis. Tumors with mutations in β-catenin are also highly addicted to this mutant gene product for their survival. We demonstrate that in MYC-induced lymphomas, combined addiction to both MYC and β-catenin can be exploited in a rational manner to prevent the emergence of therapeutic resistance.     

Catalpol protects against 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin‐induced cytotoxicity in osteoblastic MC3T3‐E1 cells

2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is a well‐known environmental contaminant that produces a wide variety of adverse effects in humans. Catalpol, a major bioactive compound enriched in the dried root of Rehmannia glutinosa, is a major iridoid glycoside that alleviates bone loss. However, the detailed mechanisms underlying the effects of catalpol remain unclear. The present study evaluated the effects of catalpol on TCDD‐induced cytotoxicity in osteoblastic MC3T3‐E1 cells. Catalpol inhibited TCDD‐induced reduction in cell viability and increases in apoptosis and autophagic activity in osteoblastic MC3T3‐E1 cells. Additionally, pretreatment with catalpol significantly decreased the nitric oxide and nitrite levels compared with a control in TCDD‐treated cells and significantly inhibited TCDD‐induced increases in the levels of cytochrome P450 1A1 and extracellular signal‐regulated kinase. Pretreatment with catalpol also effectively restored the expression of superoxide dismutase and extracellular signal‐regulated kinase 1 and significantly enhanced the expression of glutathione peroxidase 4 and osteoblast differentiation markers, including alkaline phosphatase and osterix. Taken together, these findings demonstrate that catalpol has preventive effects against TCDD‐induced damage in MC3T3‐E1 osteoblastic cells.     

Higher consumption of sugar-sweetened soft drinks increases the risk of hyperuricemia in Korean population: The Korean Multi-Rural Communities Cohort Study

Objective

The clinical implication of sugar-sweetened soft drinks on the risk of hyperuricemia has increased, especially in Western population studies. The aim of this study is to clarify the association between sugar-sweetened soft drinks and fruit drinks made from oranges and apples and the risk of hyperuricemia in the Korean Multi-Rural Communities Cohort.

Methods

A total of 9400 subjects were enrolled in the Korean Multi-Rural Communities Cohort Study, and a cross-sectional analysis was performed. Five quintiles (Q1–Q5) according to consumption of soft drinks and other fruit/fruit juices were classified and then categorized into three groups (Q1–Q3, Q4, and Q5) to assess the risk of hyperuricemia. Information on dietary intake was collected by well-trained interviewers using validated food frequency questionnaires.

Results

Higher consumption of sugar-sweetened soft drinks (Q5) increased the risk of hyperuricemia in males (adjusted OR = 1.35, 95% CI: 1.07–1.71) with a linear trend (p for trend = 0.01) and in females (adjusted OR = 1.40, 95% CI: 1.03–1.90) with no linear trend (p for trend = 0.09), compared to lower consumption (Q1–Q3). However, there were no significant differences of serum uric acid level according to the three categories of soft drink consumption, Q1–Q3, Q3, and Q5, in males (p = 0.21) or in females (p = 0.16), whereas all subjects showed statistical significance of serum uric acid level within the categories (p < 0.001). Estimated amount of soft drink intake was associated with serum uric acid level in males (β = 0.001; p = 0.01) but not in females (β = 0.0005; p = 0.10).

Conclusion

Higher consumption of sugar-sweetened soft drinks increased the risk of hyperuricemia in the Korean population, showing a differential linear trend for hyperuricemia according to gender.